Английская Википедия:China Jinping Underground Laboratory
Шаблон:Redirect Шаблон:Infobox laboratory The China Jinping Underground Laboratory (Шаблон:Zh) is a deep underground laboratory in the Jinping Mountains of Sichuan, China. The cosmic ray rate in the laboratory is under 0.2 muons/m2/day,[1] placing the lab at a depth of 6720 m.w.e.[2]Шаблон:Rp and making it the best-shielded underground laboratory in the world.[3]Шаблон:Rp The actual depth of the laboratory is Шаблон:Cvt, yet there is horizontal access so equipment may be brought in by truck.
Although the marble through which the tunnels are dug is considered "hard rock", at the great depth it presents greater geotechnical engineering challenges[4][5]Шаблон:Rp[6]Шаблон:Rp than the even harder igneous rocks in which other deep laboratories are constructed.[7]Шаблон:Rp The Шаблон:Cvt water pressure in the rock is also inconvenient. But marble has the advantage for radiation shielding of being low in radionuclides,[8][9] such as 40K, 226Ra, 232Th,[3]Шаблон:Rp and 238U.[10]Шаблон:Rp This in turn leads to low levels of radon (222Rn) in the atmosphere.[11]Шаблон:Rp
The laboratory is in Liangshan in southern Sichuan, about Шаблон:Cvt southwest of Chengdu.[3]Шаблон:Rp The closest major airport is Xichang Qingshan Airport, Шаблон:Cvt away by road.[5]Шаблон:Rp
History
The Jinping-II Dam hydroelectric power project involved excavating a number of large tunnels under the Jinping Mountains: four large Шаблон:Cvt headrace tunnels carrying water east,Шаблон:R two Шаблон:Cvt vehicular access tunnels,Шаблон:R and one water drainage tunnel. Hearing of the excavation in August 2008,Шаблон:R physicists at Tsinghua University determined that it would be an excellent location for a deep underground laboratory,Шаблон:R and negotiated with the hydropower company to excavate laboratory space in the middle of the tunnels.
A formal agreement was signed on 8 May 2009,Шаблон:R and excavation was promptly started.Шаблон:R The first phase CJPL-I, consisting of a Шаблон:Cvt main hall,Шаблон:R plus Шаблон:Cvt of access tunnel (4,000 m3 total excavation)Шаблон:R was excavated by May 2010,Шаблон:R and construction completed 12 June 2010.Шаблон:R A formal laboratory inauguration was held 12 December 2010.Шаблон:R
The laboratory is to the south of the southernmost of the seven parallel tunnels, traffic tunnel A.
The air ventilation in CJPL-I was initially inadequate, resulting in the accumulation of dust on the equipment and radon gas in the air until additional ventilation was installed.Шаблон:R
A more difficult problem is that the walls of CJPL-I were lined with ordinary concrete taken from the hydroelectric project's supply. This has a natural radioactivity higher than desirable for a low-background laboratory.Шаблон:R The second phase of construction uses materials selected for low radioactivity.Шаблон:R
CJPL-II expansion
The laboratory is currently undergoing a major (50-fold) expansion. The first phase was rapidly filled, and plans for a second were made quickly, before the excavation workers and equipment departed following completion of the hydroelectric project in 2014.[12]Шаблон:Rp
Slightly west of CJPL-I, two bypass tunnels totalling roughly Шаблон:Cvt longШаблон:R are left over from constructing the seven tunnels of the hydropower project. They are sloped criss-crossing tunnels which connect the midpoints of the five water tunnels (four headrace and one drainage) to the road tunnels beside and slightly above them. Totalling Шаблон:Cvt,Шаблон:R and originally intended to be blocked off after construction,Шаблон:R they have been donated to the laboratory and will be used for support facilities.Шаблон:R
The expansion has added Шаблон:Update after: some interconnecting access tunnels, four large experimental halls, each Шаблон:Cvt,Шаблон:R and two pits for shielding tanks below the halls' floors.Шаблон:R The China Dark Matter Experiment has a cylindrical pit, Шаблон:Cvt deep and in diameter,Шаблон:Efn which will be filled with a liquid nitrogen tank, and PandaX has an elliptical pitШаблон:Efn for a water shielding tank, Шаблон:Cvt and Шаблон:Cvt deep.Шаблон:R The halls were complete by the end of 2015,Шаблон:R, the pits by May 2016,Шаблон:R and Шаблон:As of are being fitted with ventilation systemsШаблон:R and other necessities. (This is somewhat behind expectations that they would be ready for occupation in January 2017.Шаблон:R)
When complete, it will be the world's largest underground laboratory, surpassing the current record-holder the Laboratori Nazionali del Gran Sasso (LNGS). Although greater depth and weaker rock force the halls to be narrower than the Шаблон:Cvt wide main halls of LNGS, their combined length of Шаблон:Cvt provides more floor space (Шаблон:Val vs. Шаблон:Val) than LNGS's three halls totalling Шаблон:Convert.
CJPL's halls also enclose more volume than those of LNGS. CJPL has Шаблон:ValШаблон:RШаблон:Efn in the halls proper, and an additional Шаблон:Val in the shielding pits making a total of Шаблон:Val, slightly more than LNGS's Шаблон:Val.Шаблон:Efn
Including the service areas outside the main halls, the result is Шаблон:Val of usable space,Шаблон:R more than LNGS's grand total of Шаблон:Val. CJPL's total volume of Шаблон:Val would suggest that CJPL is twice the size, but that would be misleading; all of LNGS's excavation was designed to be a laboratory, and thus can be used more efficiently than CJPL's repurposed tunnels.
| CJPL-I | CJPL-II | |
|---|---|---|
| Overall volumeШаблон:R | Шаблон:Cvt | Шаблон:Cvt |
| Laboratory area | Шаблон:Cvt | Шаблон:Cvt |
| Laboratory volume | Шаблон:Cvt | Шаблон:Cvt |
| Electrical power | 70 kVAШаблон:R | 1250 (10000) kVAШаблон:R |
| Fresh air | Шаблон:Cvt | Шаблон:Cvt |
Thanks to the laboratory's location within a major hydroelectric facility, additional electrical power is readily available. CJPL-II is supplied by two redundant 10 kV, Шаблон:Val power cables;Шаблон:R available power is temporarily limited by the 5×250 kVA step-down transformers in the laboratory (one per experiment hall, and a fifth for facilities).Шаблон:R There is likewise no shortage of waterШаблон:R for cooling high-powered equipment.
The muon flux in (and thus water equivalent depth of) CJPL-II is currently being measured,Шаблон:R and may differ slightly from CJPL-I, but it will certainly remain lower than SNOLAB in Canada and thus retain the record for the world's deepest laboratory as well.
Experiments
Experiments currently operating in CJPL are:
- China Dark Matter Experiment (CDEX), a germanium dark matter detector,[13]
- PandaX, the Particle and Astrophysical Xenon Detector for dark matter (and neutrinoless double beta decay),[3] and
- A 1-ton prototype of the planned 100-ton Jinping Neutrino Experiment,[14][15]Шаблон:R an experiment taking advantage of CJPL's location far from nuclear reactors, and thus having the lowest flux of reactor neutrinos of any underground laboratory,Шаблон:R to do precision measurements of solar- and geoneutrinos.Шаблон:R
Also operating in the laboratory is a low background facility using a high purity germanium detector, for measuring very low levels of radioactivity.Шаблон:R This is not a physics experiment itself, but tests materials intended for use in the experiments. It also tests materials used to construct CJPL-II.Шаблон:R
Experiments currently planned for CJPL-II are:Шаблон:R
- a larger, tonne-scale version of CDEX,Шаблон:R
- a larger, tonne-scale version of PandaX,Шаблон:R
- Jinping Underground Nuclear Astrophysics (JUNA), an experiment to measure the rates of astrophysically important stellar nuclear reactions,Шаблон:R and
- a possible liquid argon dark matter detector.Шаблон:R
Proposals also exist for:
- CUPID (CUORE Upgrade with Particle Identification), a neutrinoless double beta decay experiment,Шаблон:R and
- a directional dark matter detector by the MIMAC (MIcro-tpc MAtrix of Chambers) collaboration,Шаблон:R as a follow-on to their detector currently operating at the Modane Underground Laboratory.[16]
Notes
References
External links
- CJPL home page (Tsinghua University)
- Jinping Neutrino Experiment home page (Tsinghua University)
- CJPL GitHub page
- Symposium on Future Applications of Germanium Detectors in Fundamental Research in Beijing, with multiple CJPL presentations
- A Town Meeting for the 2nd-phase Development of the China Jinping Underground Laboratory (Sept. 8, 2013) at the 13th International Conference on Topics in Astroparticle and Underground Physics
- CJPL 2015 conference presentations Шаблон:Webarchive
Шаблон:Underground laboratories
- ↑ Ошибка цитирования Неверный тег
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<ref>; для сносокPhase2не указан текст - ↑ 3,0 3,1 3,2 3,3 Ошибка цитирования Неверный тег
<ref>; для сносокPandaXне указан текст - ↑ Ошибка цитирования Неверный тег
<ref>; для сносокRockGeotechне указан текст - ↑ 5,0 5,1 Ошибка цитирования Неверный тег
<ref>; для сносокStatus2013не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>; для сносокTAUP2015не указан текст - ↑ Шаблон:Cite conference
- ↑ Ошибка цитирования Неверный тег
<ref>; для сносокChui10не указан текст - ↑ Ошибка цитирования Неверный тег
<ref>; для сносокStricklandне указан текст - ↑ Шаблон:Cite conference
- ↑ Ошибка цитирования Неверный тег
<ref>; для сносокJuly2016не указан текст - ↑ Шаблон:Cite conference
- ↑ Ошибка цитирования Неверный тег
<ref>; для сносокCDEXне указан текст - ↑ Шаблон:Cite conference
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
